001 /*
002 * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.io;
027
028 /**
029 * A data input stream lets an application read primitive Java data
030 * types from an underlying input stream in a machine-independent
031 * way. An application uses a data output stream to write data that
032 * can later be read by a data input stream.
033 * <p>
034 * DataInputStream is not necessarily safe for multithreaded access.
035 * Thread safety is optional and is the responsibility of users of
036 * methods in this class.
037 *
038 * @author Arthur van Hoff
039 * @version 1.83, 05/05/07
040 * @see java.io.DataOutputStream
041 * @since JDK1.0
042 */
043 public class DataInputStream extends FilterInputStream implements
044 DataInput {
045
046 /**
047 * Creates a DataInputStream that uses the specified
048 * underlying InputStream.
049 *
050 * @param in the specified input stream
051 */
052 public DataInputStream(InputStream in) {
053 super (in);
054 }
055
056 /**
057 * working arrays initialized on demand by readUTF
058 */
059 private byte bytearr[] = new byte[80];
060 private char chararr[] = new char[80];
061
062 /**
063 * Reads some number of bytes from the contained input stream and
064 * stores them into the buffer array <code>b</code>. The number of
065 * bytes actually read is returned as an integer. This method blocks
066 * until input data is available, end of file is detected, or an
067 * exception is thrown.
068 *
069 * <p>If <code>b</code> is null, a <code>NullPointerException</code> is
070 * thrown. If the length of <code>b</code> is zero, then no bytes are
071 * read and <code>0</code> is returned; otherwise, there is an attempt
072 * to read at least one byte. If no byte is available because the
073 * stream is at end of file, the value <code>-1</code> is returned;
074 * otherwise, at least one byte is read and stored into <code>b</code>.
075 *
076 * <p>The first byte read is stored into element <code>b[0]</code>, the
077 * next one into <code>b[1]</code>, and so on. The number of bytes read
078 * is, at most, equal to the length of <code>b</code>. Let <code>k</code>
079 * be the number of bytes actually read; these bytes will be stored in
080 * elements <code>b[0]</code> through <code>b[k-1]</code>, leaving
081 * elements <code>b[k]</code> through <code>b[b.length-1]</code>
082 * unaffected.
083 *
084 * <p>The <code>read(b)</code> method has the same effect as:
085 * <blockquote><pre>
086 * read(b, 0, b.length)
087 * </pre></blockquote>
088 *
089 * @param b the buffer into which the data is read.
090 * @return the total number of bytes read into the buffer, or
091 * <code>-1</code> if there is no more data because the end
092 * of the stream has been reached.
093 * @exception IOException if the first byte cannot be read for any reason
094 * other than end of file, the stream has been closed and the underlying
095 * input stream does not support reading after close, or another I/O
096 * error occurs.
097 * @see java.io.FilterInputStream#in
098 * @see java.io.InputStream#read(byte[], int, int)
099 */
100 public final int read(byte b[]) throws IOException {
101 return in.read(b, 0, b.length);
102 }
103
104 /**
105 * Reads up to <code>len</code> bytes of data from the contained
106 * input stream into an array of bytes. An attempt is made to read
107 * as many as <code>len</code> bytes, but a smaller number may be read,
108 * possibly zero. The number of bytes actually read is returned as an
109 * integer.
110 *
111 * <p> This method blocks until input data is available, end of file is
112 * detected, or an exception is thrown.
113 *
114 * <p> If <code>len</code> is zero, then no bytes are read and
115 * <code>0</code> is returned; otherwise, there is an attempt to read at
116 * least one byte. If no byte is available because the stream is at end of
117 * file, the value <code>-1</code> is returned; otherwise, at least one
118 * byte is read and stored into <code>b</code>.
119 *
120 * <p> The first byte read is stored into element <code>b[off]</code>, the
121 * next one into <code>b[off+1]</code>, and so on. The number of bytes read
122 * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
123 * bytes actually read; these bytes will be stored in elements
124 * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
125 * leaving elements <code>b[off+</code><i>k</i><code>]</code> through
126 * <code>b[off+len-1]</code> unaffected.
127 *
128 * <p> In every case, elements <code>b[0]</code> through
129 * <code>b[off]</code> and elements <code>b[off+len]</code> through
130 * <code>b[b.length-1]</code> are unaffected.
131 *
132 * @param b the buffer into which the data is read.
133 * @param off the start offset in the destination array <code>b</code>
134 * @param len the maximum number of bytes read.
135 * @return the total number of bytes read into the buffer, or
136 * <code>-1</code> if there is no more data because the end
137 * of the stream has been reached.
138 * @exception NullPointerException If <code>b</code> is <code>null</code>.
139 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
140 * <code>len</code> is negative, or <code>len</code> is greater than
141 * <code>b.length - off</code>
142 * @exception IOException if the first byte cannot be read for any reason
143 * other than end of file, the stream has been closed and the underlying
144 * input stream does not support reading after close, or another I/O
145 * error occurs.
146 * @see java.io.FilterInputStream#in
147 * @see java.io.InputStream#read(byte[], int, int)
148 */
149 public final int read(byte b[], int off, int len)
150 throws IOException {
151 return in.read(b, off, len);
152 }
153
154 /**
155 * See the general contract of the <code>readFully</code>
156 * method of <code>DataInput</code>.
157 * <p>
158 * Bytes
159 * for this operation are read from the contained
160 * input stream.
161 *
162 * @param b the buffer into which the data is read.
163 * @exception EOFException if this input stream reaches the end before
164 * reading all the bytes.
165 * @exception IOException the stream has been closed and the contained
166 * input stream does not support reading after close, or
167 * another I/O error occurs.
168 * @see java.io.FilterInputStream#in
169 */
170 public final void readFully(byte b[]) throws IOException {
171 readFully(b, 0, b.length);
172 }
173
174 /**
175 * See the general contract of the <code>readFully</code>
176 * method of <code>DataInput</code>.
177 * <p>
178 * Bytes
179 * for this operation are read from the contained
180 * input stream.
181 *
182 * @param b the buffer into which the data is read.
183 * @param off the start offset of the data.
184 * @param len the number of bytes to read.
185 * @exception EOFException if this input stream reaches the end before
186 * reading all the bytes.
187 * @exception IOException the stream has been closed and the contained
188 * input stream does not support reading after close, or
189 * another I/O error occurs.
190 * @see java.io.FilterInputStream#in
191 */
192 public final void readFully(byte b[], int off, int len)
193 throws IOException {
194 if (len < 0)
195 throw new IndexOutOfBoundsException();
196 int n = 0;
197 while (n < len) {
198 int count = in.read(b, off + n, len - n);
199 if (count < 0)
200 throw new EOFException();
201 n += count;
202 }
203 }
204
205 /**
206 * See the general contract of the <code>skipBytes</code>
207 * method of <code>DataInput</code>.
208 * <p>
209 * Bytes for this operation are read from the contained
210 * input stream.
211 *
212 * @param n the number of bytes to be skipped.
213 * @return the actual number of bytes skipped.
214 * @exception IOException if the contained input stream does not support
215 * seek, or the stream has been closed and
216 * the contained input stream does not support
217 * reading after close, or another I/O error occurs.
218 */
219 public final int skipBytes(int n) throws IOException {
220 int total = 0;
221 int cur = 0;
222
223 while ((total < n) && ((cur = (int) in.skip(n - total)) > 0)) {
224 total += cur;
225 }
226
227 return total;
228 }
229
230 /**
231 * See the general contract of the <code>readBoolean</code>
232 * method of <code>DataInput</code>.
233 * <p>
234 * Bytes for this operation are read from the contained
235 * input stream.
236 *
237 * @return the <code>boolean</code> value read.
238 * @exception EOFException if this input stream has reached the end.
239 * @exception IOException the stream has been closed and the contained
240 * input stream does not support reading after close, or
241 * another I/O error occurs.
242 * @see java.io.FilterInputStream#in
243 */
244 public final boolean readBoolean() throws IOException {
245 int ch = in.read();
246 if (ch < 0)
247 throw new EOFException();
248 return (ch != 0);
249 }
250
251 /**
252 * See the general contract of the <code>readByte</code>
253 * method of <code>DataInput</code>.
254 * <p>
255 * Bytes
256 * for this operation are read from the contained
257 * input stream.
258 *
259 * @return the next byte of this input stream as a signed 8-bit
260 * <code>byte</code>.
261 * @exception EOFException if this input stream has reached the end.
262 * @exception IOException the stream has been closed and the contained
263 * input stream does not support reading after close, or
264 * another I/O error occurs.
265 * @see java.io.FilterInputStream#in
266 */
267 public final byte readByte() throws IOException {
268 int ch = in.read();
269 if (ch < 0)
270 throw new EOFException();
271 return (byte) (ch);
272 }
273
274 /**
275 * See the general contract of the <code>readUnsignedByte</code>
276 * method of <code>DataInput</code>.
277 * <p>
278 * Bytes
279 * for this operation are read from the contained
280 * input stream.
281 *
282 * @return the next byte of this input stream, interpreted as an
283 * unsigned 8-bit number.
284 * @exception EOFException if this input stream has reached the end.
285 * @exception IOException the stream has been closed and the contained
286 * input stream does not support reading after close, or
287 * another I/O error occurs.
288 * @see java.io.FilterInputStream#in
289 */
290 public final int readUnsignedByte() throws IOException {
291 int ch = in.read();
292 if (ch < 0)
293 throw new EOFException();
294 return ch;
295 }
296
297 /**
298 * See the general contract of the <code>readShort</code>
299 * method of <code>DataInput</code>.
300 * <p>
301 * Bytes
302 * for this operation are read from the contained
303 * input stream.
304 *
305 * @return the next two bytes of this input stream, interpreted as a
306 * signed 16-bit number.
307 * @exception EOFException if this input stream reaches the end before
308 * reading two bytes.
309 * @exception IOException the stream has been closed and the contained
310 * input stream does not support reading after close, or
311 * another I/O error occurs.
312 * @see java.io.FilterInputStream#in
313 */
314 public final short readShort() throws IOException {
315 int ch1 = in.read();
316 int ch2 = in.read();
317 if ((ch1 | ch2) < 0)
318 throw new EOFException();
319 return (short) ((ch1 << 8) + (ch2 << 0));
320 }
321
322 /**
323 * See the general contract of the <code>readUnsignedShort</code>
324 * method of <code>DataInput</code>.
325 * <p>
326 * Bytes
327 * for this operation are read from the contained
328 * input stream.
329 *
330 * @return the next two bytes of this input stream, interpreted as an
331 * unsigned 16-bit integer.
332 * @exception EOFException if this input stream reaches the end before
333 * reading two bytes.
334 * @exception IOException the stream has been closed and the contained
335 * input stream does not support reading after close, or
336 * another I/O error occurs.
337 * @see java.io.FilterInputStream#in
338 */
339 public final int readUnsignedShort() throws IOException {
340 int ch1 = in.read();
341 int ch2 = in.read();
342 if ((ch1 | ch2) < 0)
343 throw new EOFException();
344 return (ch1 << 8) + (ch2 << 0);
345 }
346
347 /**
348 * See the general contract of the <code>readChar</code>
349 * method of <code>DataInput</code>.
350 * <p>
351 * Bytes
352 * for this operation are read from the contained
353 * input stream.
354 *
355 * @return the next two bytes of this input stream, interpreted as a
356 * <code>char</code>.
357 * @exception EOFException if this input stream reaches the end before
358 * reading two bytes.
359 * @exception IOException the stream has been closed and the contained
360 * input stream does not support reading after close, or
361 * another I/O error occurs.
362 * @see java.io.FilterInputStream#in
363 */
364 public final char readChar() throws IOException {
365 int ch1 = in.read();
366 int ch2 = in.read();
367 if ((ch1 | ch2) < 0)
368 throw new EOFException();
369 return (char) ((ch1 << 8) + (ch2 << 0));
370 }
371
372 /**
373 * See the general contract of the <code>readInt</code>
374 * method of <code>DataInput</code>.
375 * <p>
376 * Bytes
377 * for this operation are read from the contained
378 * input stream.
379 *
380 * @return the next four bytes of this input stream, interpreted as an
381 * <code>int</code>.
382 * @exception EOFException if this input stream reaches the end before
383 * reading four bytes.
384 * @exception IOException the stream has been closed and the contained
385 * input stream does not support reading after close, or
386 * another I/O error occurs.
387 * @see java.io.FilterInputStream#in
388 */
389 public final int readInt() throws IOException {
390 int ch1 = in.read();
391 int ch2 = in.read();
392 int ch3 = in.read();
393 int ch4 = in.read();
394 if ((ch1 | ch2 | ch3 | ch4) < 0)
395 throw new EOFException();
396 return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
397 }
398
399 private byte readBuffer[] = new byte[8];
400
401 /**
402 * See the general contract of the <code>readLong</code>
403 * method of <code>DataInput</code>.
404 * <p>
405 * Bytes
406 * for this operation are read from the contained
407 * input stream.
408 *
409 * @return the next eight bytes of this input stream, interpreted as a
410 * <code>long</code>.
411 * @exception EOFException if this input stream reaches the end before
412 * reading eight bytes.
413 * @exception IOException the stream has been closed and the contained
414 * input stream does not support reading after close, or
415 * another I/O error occurs.
416 * @see java.io.FilterInputStream#in
417 */
418 public final long readLong() throws IOException {
419 readFully(readBuffer, 0, 8);
420 return (((long) readBuffer[0] << 56)
421 + ((long) (readBuffer[1] & 255) << 48)
422 + ((long) (readBuffer[2] & 255) << 40)
423 + ((long) (readBuffer[3] & 255) << 32)
424 + ((long) (readBuffer[4] & 255) << 24)
425 + ((readBuffer[5] & 255) << 16)
426 + ((readBuffer[6] & 255) << 8) + ((readBuffer[7] & 255) << 0));
427 }
428
429 /**
430 * See the general contract of the <code>readFloat</code>
431 * method of <code>DataInput</code>.
432 * <p>
433 * Bytes
434 * for this operation are read from the contained
435 * input stream.
436 *
437 * @return the next four bytes of this input stream, interpreted as a
438 * <code>float</code>.
439 * @exception EOFException if this input stream reaches the end before
440 * reading four bytes.
441 * @exception IOException the stream has been closed and the contained
442 * input stream does not support reading after close, or
443 * another I/O error occurs.
444 * @see java.io.DataInputStream#readInt()
445 * @see java.lang.Float#intBitsToFloat(int)
446 */
447 public final float readFloat() throws IOException {
448 return Float.intBitsToFloat(readInt());
449 }
450
451 /**
452 * See the general contract of the <code>readDouble</code>
453 * method of <code>DataInput</code>.
454 * <p>
455 * Bytes
456 * for this operation are read from the contained
457 * input stream.
458 *
459 * @return the next eight bytes of this input stream, interpreted as a
460 * <code>double</code>.
461 * @exception EOFException if this input stream reaches the end before
462 * reading eight bytes.
463 * @exception IOException the stream has been closed and the contained
464 * input stream does not support reading after close, or
465 * another I/O error occurs.
466 * @see java.io.DataInputStream#readLong()
467 * @see java.lang.Double#longBitsToDouble(long)
468 */
469 public final double readDouble() throws IOException {
470 return Double.longBitsToDouble(readLong());
471 }
472
473 private char lineBuffer[];
474
475 /**
476 * See the general contract of the <code>readLine</code>
477 * method of <code>DataInput</code>.
478 * <p>
479 * Bytes
480 * for this operation are read from the contained
481 * input stream.
482 *
483 * @deprecated This method does not properly convert bytes to characters.
484 * As of JDK 1.1, the preferred way to read lines of text is via the
485 * <code>BufferedReader.readLine()</code> method. Programs that use the
486 * <code>DataInputStream</code> class to read lines can be converted to use
487 * the <code>BufferedReader</code> class by replacing code of the form:
488 * <blockquote><pre>
489 * DataInputStream d = new DataInputStream(in);
490 * </pre></blockquote>
491 * with:
492 * <blockquote><pre>
493 * BufferedReader d
494 * = new BufferedReader(new InputStreamReader(in));
495 * </pre></blockquote>
496 *
497 * @return the next line of text from this input stream.
498 * @exception IOException if an I/O error occurs.
499 * @see java.io.BufferedReader#readLine()
500 * @see java.io.FilterInputStream#in
501 */
502 @Deprecated
503 public final String readLine() throws IOException {
504 char buf[] = lineBuffer;
505
506 if (buf == null) {
507 buf = lineBuffer = new char[128];
508 }
509
510 int room = buf.length;
511 int offset = 0;
512 int c;
513
514 loop: while (true) {
515 switch (c = in.read()) {
516 case -1:
517 case '\n':
518 break loop;
519
520 case '\r':
521 int c2 = in.read();
522 if ((c2 != '\n') && (c2 != -1)) {
523 if (!(in instanceof PushbackInputStream)) {
524 this .in = new PushbackInputStream(in);
525 }
526 ((PushbackInputStream) in).unread(c2);
527 }
528 break loop;
529
530 default:
531 if (--room < 0) {
532 buf = new char[offset + 128];
533 room = buf.length - offset - 1;
534 System.arraycopy(lineBuffer, 0, buf, 0, offset);
535 lineBuffer = buf;
536 }
537 buf[offset++] = (char) c;
538 break;
539 }
540 }
541 if ((c == -1) && (offset == 0)) {
542 return null;
543 }
544 return String.copyValueOf(buf, 0, offset);
545 }
546
547 /**
548 * See the general contract of the <code>readUTF</code>
549 * method of <code>DataInput</code>.
550 * <p>
551 * Bytes
552 * for this operation are read from the contained
553 * input stream.
554 *
555 * @return a Unicode string.
556 * @exception EOFException if this input stream reaches the end before
557 * reading all the bytes.
558 * @exception IOException the stream has been closed and the contained
559 * input stream does not support reading after close, or
560 * another I/O error occurs.
561 * @exception UTFDataFormatException if the bytes do not represent a valid
562 * modified UTF-8 encoding of a string.
563 * @see java.io.DataInputStream#readUTF(java.io.DataInput)
564 */
565 public final String readUTF() throws IOException {
566 return readUTF(this );
567 }
568
569 /**
570 * Reads from the
571 * stream <code>in</code> a representation
572 * of a Unicode character string encoded in
573 * <a href="DataInput.html#modified-utf-8">modified UTF-8</a> format;
574 * this string of characters is then returned as a <code>String</code>.
575 * The details of the modified UTF-8 representation
576 * are exactly the same as for the <code>readUTF</code>
577 * method of <code>DataInput</code>.
578 *
579 * @param in a data input stream.
580 * @return a Unicode string.
581 * @exception EOFException if the input stream reaches the end
582 * before all the bytes.
583 * @exception IOException the stream has been closed and the contained
584 * input stream does not support reading after close, or
585 * another I/O error occurs.
586 * @exception UTFDataFormatException if the bytes do not represent a
587 * valid modified UTF-8 encoding of a Unicode string.
588 * @see java.io.DataInputStream#readUnsignedShort()
589 */
590 public final static String readUTF(DataInput in) throws IOException {
591 int utflen = in.readUnsignedShort();
592 byte[] bytearr = null;
593 char[] chararr = null;
594 if (in instanceof DataInputStream) {
595 DataInputStream dis = (DataInputStream) in;
596 if (dis.bytearr.length < utflen) {
597 dis.bytearr = new byte[utflen * 2];
598 dis.chararr = new char[utflen * 2];
599 }
600 chararr = dis.chararr;
601 bytearr = dis.bytearr;
602 } else {
603 bytearr = new byte[utflen];
604 chararr = new char[utflen];
605 }
606
607 int c, char2, char3;
608 int count = 0;
609 int chararr_count = 0;
610
611 in.readFully(bytearr, 0, utflen);
612
613 while (count < utflen) {
614 c = (int) bytearr[count] & 0xff;
615 if (c > 127)
616 break;
617 count++;
618 chararr[chararr_count++] = (char) c;
619 }
620
621 while (count < utflen) {
622 c = (int) bytearr[count] & 0xff;
623 switch (c >> 4) {
624 case 0:
625 case 1:
626 case 2:
627 case 3:
628 case 4:
629 case 5:
630 case 6:
631 case 7:
632 /* 0xxxxxxx*/
633 count++;
634 chararr[chararr_count++] = (char) c;
635 break;
636 case 12:
637 case 13:
638 /* 110x xxxx 10xx xxxx*/
639 count += 2;
640 if (count > utflen)
641 throw new UTFDataFormatException(
642 "malformed input: partial character at end");
643 char2 = (int) bytearr[count - 1];
644 if ((char2 & 0xC0) != 0x80)
645 throw new UTFDataFormatException(
646 "malformed input around byte " + count);
647 chararr[chararr_count++] = (char) (((c & 0x1F) << 6) | (char2 & 0x3F));
648 break;
649 case 14:
650 /* 1110 xxxx 10xx xxxx 10xx xxxx */
651 count += 3;
652 if (count > utflen)
653 throw new UTFDataFormatException(
654 "malformed input: partial character at end");
655 char2 = (int) bytearr[count - 2];
656 char3 = (int) bytearr[count - 1];
657 if (((char2 & 0xC0) != 0x80)
658 || ((char3 & 0xC0) != 0x80))
659 throw new UTFDataFormatException(
660 "malformed input around byte "
661 + (count - 1));
662 chararr[chararr_count++] = (char) (((c & 0x0F) << 12)
663 | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
664 break;
665 default:
666 /* 10xx xxxx, 1111 xxxx */
667 throw new UTFDataFormatException(
668 "malformed input around byte " + count);
669 }
670 }
671 // The number of chars produced may be less than utflen
672 return new String(chararr, 0, chararr_count);
673 }
674 }
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